As a followup to T355449: Ensure wikimedia.org adheres to Google's sender guidelines, where @thcipriani wrote:
I realize you mentioned Phab and Gerrit are out of scope, but for the purposes of gathering data: looking at exim logs, Phab sent 10,740 emails to gmail addresses yesterday and 7195 today (since we did the phab upgrade on Saturday, I only have two days of historical data on disk there). Gerrit has hovered between 2k–3k emails to gmail addresses per day.
From sender guidelines:
If you send more than 5,000 message per day, your marketing and subscribed messages must support one-click unsubscribe.
To set up one-click unsubscribe, include both of these headers in outgoing messages:
- List-Unsubscribe-Post: List-Unsubscribe=One-Click
- List-Unsubscribe: https://solarmora.com/unsubscribe/example
Phab/Phorge mails sent have a preference management link in the body, but no List-Unsubscribe, let alone List-Unsubscribe-Post. A quick search didn't find anything about this upstream.
Requirements for all senders
- Set up SPF or DKIM email authentication for your domain.
- Ensure that sending domains or IPs have valid forward and reverse DNS records, also referred to as PTR records.
- Use a TLS connection for transmitting email.
- Keep spam rates reported in Postmaster Tools below 0.10% and avoid ever reaching a spam rate of 0.30% or higher.
- Format messages according to the Internet Message Format standard (RFC 5322).
- Don’t impersonate Gmail From: headers. Gmail will begin using a DMARC quarantine enforcement policy, and impersonating Gmail From: headers might impact your email delivery.
- If you regularly forward email, including using mailing lists or inbound gateways, add ARC headers to outgoing email.
Requirements for high-volume senders
I don’t have data on this atm but I would not be surprised if we’re over the 5k emails per day threshold.
- Set up DMARC email authentication for your sending domain. Your DMARC enforcement policy can be set to none.
- For direct mail, the domain in the sender’s From: header must be aligned with either the SPF domain or the DKIM domain. This is required to pass DMARC alignment.
- Marketing messages and subscribed messages must support one-click unsubscribe, and include a clearly visible unsubscribe link in the message body.